Method 1. First make the All In One Sponge Cake in your mixer. Cook them in two square cake tins. 2. Let the cakes cool down and cut them into a nice square shape. (You can use any bits of cake you cut off to make the Truffles recipe). 3. Sieve icing sugar and cocoa powder together and add warm water, a little bit at a time. Don’t add too much water or the icing will be too runny. 4. Spread icing over the cakes and leave until it’s almost hard. 5. Cut each cake in half and then each half into 4 pieces. This will give you 16 little cakes. 6. Make a line across the middle of each small cake. Then white chocolate drops to make the domino dots.